D. J. Bernstein
The tcpclient program
tcpclient creates an outgoing TCP connection.
tcpclient opts host port prog
is a series of getopt-style options.
host is one argument.
port is one argument.
prog consists of one or more arguments.
tcpclient attempts to connect to a TCP server.
If it is successful,
it runs prog,
with descriptor 6 reading from the network
and descriptor 7 writing to the network.
It also sets up several
The server's address is given by host and port.
port may be a name from /etc/services or a number.
host may be 0,
referring to the local machine,
or a dotted-decimal IP address,
or a host name;
it is fed through
If the server has several IP addresses,
tcpclient tries each address in turn.
- -q: Quiet. Do not print error messages.
- -Q: (Default.) Print error messages.
- -v: Verbose. Print error messages and status messages.
- -T x+y:
Give up on the connection attempt after x+y seconds.
When a host has several IP addresses,
tcpclient tries to connect to the first IP address,
waits x seconds,
tries to connect to the second IP address,
waits x seconds, etc.;
then it retries each address that timed out,
waiting y seconds per address.
You may omit +y to skip the second try.
Before version 0.88, tcpclient will use only x
- -i localip: Use localip
as the IP address for the local side of the connection;
quit if localip is not available.
Normally tcpclient lets the operating system choose an address.
- -p localport: Use localport
as the TCP port for the local side of the connection;
quit if localport is not available.
Normally tcpclient lets the operating system choose a port.
- -d: Delay sending data for a fraction of a second
whenever the remote host is responding slowly.
This is currently the default, but it may not be in the future;
if you want it, set it explicitly.
- -D: Never delay sending data; enable TCP_NODELAY.
- -h: (Default.)
Look up the remote host name in DNS
to set the environment variable $TCPREMOTEHOST.
Do not look up the remote host name in DNS;
remove the environment variable $TCPREMOTEHOST.
- -l localname:
Do not look up the local host name in DNS;
use localname for the environment variable $TCPLOCALHOST.
A common choice for localname is 0.
- -r: (Default.)
Attempt to obtain $TCPREMOTEINFO from the remote host.
Do not attempt to obtain $TCPREMOTEINFO from the remote host.
- -t n:
Give up on the $TCPREMOTEINFO connection attempt
after n seconds.